ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Technology for processing oil waste and producing construction material

Nadira Yusupova, Abdugaffor Khurmamatov, Salamat Berdimbetov, and Temirbek Naubeev

Almalyk State Technical Institute, Almalyk, Uzbekistan

E-mail: nadira__87@mail.ru

Received: 15 May 2025  Accepted: 5 January 2026

Abstract:

This study investigates processes for recycling oil sludge to produce construction materials. We determined the water content using the Dean–Stark method, mechanical impurities via extraction with a Soxhlet apparatus, and metal content through X-ray spectroscopy. The concentrations of heavy metals in oil sludge were as follows: Pb—0.035 kg/t; Ni—0.011 kg/t; Zn—0.0225 kg/t; Cr—0.01 kg/t; Cu—0.004 kg/t. Experiments were carried out involving the mixing of oil sludge with emulsifier and demulsifier, followed by separation using a centrifuge. The most effective methods of mixing and centrifugation were examined. As a result of cleaning mechanical impurities in the oil sludge with light naphtha, the concentration of mechanical impurities was reduced to 0.05%. During the production of expanded clay aggregate, optimal ratios of oil sludge and bentonite were determined, and the most suitable drying and heating modes in the expanded clay production process were analyzed. The density of expanded clay was determined, along with the calculation of shape coefficient, water absorption, bloating index, and strength. Samples containing 15% and 20% oil sludge retained their shape better, while samples with 25% and 30% oil sludge showed a loss in strength, with some beginning to disintegrate. At temperatures up to 1000 °C, a mixture with 20% oil sludge and 80% bentonite maintained its shape and demonstrated uniform firing without cracks. Meanwhile, mixtures with higher oil sludge content began to degrade at 1000 °C: the 25–75% mixture cracked at 1000 °C, and the 30–70% mixture completely disintegrated. Tests on bentonite clays showed their compliance with the requirements of GOST 9169-75 (clause 10) in terms of chemical composition, presence of coarse inclusions, expanded clay, bloating capacity and plasticity. Therefore, it was decided to continue research using a combined sample obtained by thorough mixing of the oil sludge.

Keywords: oil sludge; expanded clay; bentonite; mechanical impurities; X-ray spectroscopy; demulsifier

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-026-04652-5

Chemical Papers 80 (4) 3813–3825 (2026)